1. Field of the Invention
The present invention relates to retaining devices, and particularly to a retaining device which can securely retain expansion cards in a computer chassis.
2. Description of the Prior Art
A computer typically includes a chassis that encloses circuit components, such as processors, memory chips, peripheral interface devices and other circuit elements. The core circuit components, such as the processors and the memory chips, are often mounted on a single printed circuit board, such as a motherboard. It is often desirable to provide the computer with expansion ports or slots for attaching additional printed circuit cards (“expansion cards”) having additional capabilities.
In one conventional arrangement, the expansion slots are provided on the motherboard. One drawback with this approach is that the expansion slots occupy valuable space on the motherboard. And nowadays the trend of the computer enclosure is small and thin. So a new type of computer enclosure has a limited height that cannot accommodate an expansion card directly mounted on the motherboard. One approach to addressing this drawback is to attach an intermediate riser card to a single slot of the motherboard and attach a plurality of expansion cards to the riser card.
Such an arrangement for expansion card is disclosed in U.S. Pat. No. 5,835,346. A computer chassis is partitioned into first and second regions by a partition wall. A motherboard is positioned within the first region along a bottom wall of the chassis. A riser card abutting the partition wall vertically interfaces with the motherboard. A series of horizontal option card interfaces are located above each other on the riser card within the first region of the enclosure each for interfacing with a corresponding option card and to position the option cards horizontally over the motherboard. However, the riser card is inserted in the motherboard directly and the option cards are inserted in the riser cards and then mounted in a back wall of the enclosure. When the computer is moved to anther place or sustains external shocks, the riser cards and the option cards are prone to be loosed or detached from the motherboard and the riser cards, respectively.